Concrete joint seal



Dec. 31, 1968 c. CIMINI CONCRETE JOINT SEAL I of 5 Sheet Filed Oct. 10,1966 FiG.l

Dec. 31, 1968 c. CIMINI CONCRETE JOINT SEAL Sheet Filed Oct. 10. 1966FIG. 2

Dec. 31, 1968 c. CIMINI 3,418,898

CONCRETE JOINT SEAL Filed Oct. 10. 1966 Sheet 3 of 5 FIG? 3,418,898CONCRETE JOINT SEAL Claude Cimini, Cocliituate, Mass, assignor to W. R.Grace & Co., Cambridge, Mass., a corporation of Connecticut Filed Oct.10, 1966, Ser. No. 585,620 3 Claims. (CI. 9418) ABSTRACT OF THEDISCLOSURE A preformed seal for sealing joints in concrete structures isdisclosed wherein a resilient, distortable chevronshaped sealing member(composed, e.g., of neoprene) is positioned between the upper marginalportions of two opposed, metal strips. The upper portions of the stripsare imbedded in the side walls of the sealing member. Tie wires arewrapped around the periphery of the joint seal to maintain compressionof the sealing member which tie wires can be severed subsequent to theinsertion of the joint seal in the wet concrete structure to permitexpansion of the sealing member.

This invention relates to means for sealing the joints in concretestructures.

As the description proceeds, it will become obvious that the seal hasutility in, and may be used with all types of joints between concretesections, but because the seal has special advantages in sealing thejoints between pavement slabs, aprons, and fioorings, it will bedescribed in relation to such uses.

Concrete expands and contracts. Not only is there an initial contractionas the wet concrete hardens, but thereafter the concrete mass expandsand contracts in response to the changes in temperature. Although themovement is small, it still is sufiicient to enlarge the gap betweenadjacent slabs to such a degree that water can easily penetrate and soakthe subgrade. But an even worse difiiculty occurs when, as in the caseof a roadway, traffic pounds dust, sand, and road debris into thejoints. It is conventional, therefore, to seal the joints betweenadjacent concrete slabs in such a manner that a tight, leak-proof sealis maintained at all times despite the linear motions of the concreteslab.

Conventionally, the joints between concrete slabs have been sealed bypouring a melted thermoplastic compound into the joint space. But morerecently, a much more effective seal has been introduced comprising apreformed, expansible rubber member held between steel reinforcingmembers. Under ordinary conditions, these seals give excellentperformance and prevent, to a far better degree than the poured-in sealswhich previously were used, the penetration of dirt, moisture, and roaddebris into the joint space.

In the northern tier of States, however, where it has become thepractice of the highway departments to plow roads completely bare, andlower plow blades until they contact with the concrete surface as theplowing progresses, a number of such seals have been damaged during thewinter months. Damage occurs where the concrete surface has worn belowthe level of the steel, or where uneven finishing allows the steelmargin to project above the concrete surface, for then the strip can bestruck by the blade of a plow, causing a considerable length of seal tobe ripped out of the concrete. Not only is the seal destroyed, butsubstantial repairs to the margins of the slab may be required.

I have discovered that if the upper margins of the metal reinforcingstrips are bedded in the rubber member itself and thus no metal isexposed at the wearing surface of the joint seal, the plow blade merelycauses the sealing nite States Patent 3,418,898 Patented Dec. 31, 1968material to deflect, and never catches on or tears the reinforcement.

The principal object of this invention, accordingly, is to prevent theoccurrence of such plow-caused damage, and additionally to produce apresealed expansion or construction joint which will expand and contractwith the seasonal movement of the concrete slab, which will maintain atightly sealed joint, well protected against the penetration of dirt,sand, and water; to produce a joint which, once installed, either by ajoint-planting machine or by hand, permits all main components of theseal to remain in place; to provide a joint seal which eliminates thestep of packing or pouring a distortable filling material into the jointspace, and particularly to produce a seal in which no reinforcing orsupporting element is exposed directly at the surface of the slab, andto protect the reinforcing structures from the action of the weather andthe wear of traffic.

The accomplishment of these and other objects will become apparent asthis specification proceeds, and from the drawings in which:

FIG. 1 is a transverse cross-section of the improved joint seal,

FIG. 2 is a transverse cross-section of an alternative form of theinvention,

FIG. 3 is a transverse cross-section of a portion of one of the sidemembers Showing the means of anchoring the seal to the concrete,

FIG. 4 is a vertical cross-section of the collapsed sealing strip, and

FIG. 5 is a vertical cross-section of the seal embedded between twoconcrete slabs.

The seal 10 comprises two especially contoured metallic strips 11 and 12of the length sufficient to extend uninterruptedly either across oralong one entire margin of a concrete slab. The upper, longitudinalmargins of each strip are out-turned and beaded as indicated at 13. Ashoulder 14 is formed in each strip, spaced from the beaded margins 13at approximately one quarter of the distance between top and lowermargins. The lower margins of the strip are out-turned to form thehook-type, outwardly directed anchors 1515 which are upturned at anangle of approximately 45. In use, the anchors project into the concretemass.

The sides of the strips 11 and 12 in the area immediately beneath theshoulder are pierced with a series of slots, and the metal thus freed isthrust outwardly to form a number of anchoring tongues 16, asillustrated in FIG. 2. p

The sealing element 17 itself is formed of a resilient, extensiblesubstance which generally can be described as an oil-and-ozone-resistantrubber, surmounts both of the strips 11 and 12 at their upper margins.

Seal 17 is securely vulcanized to each strip, and extends from a shortdistance above the margins 13 to the shoulders 14.

One, and the preferred, method of manufacture follows: the steel strips11 are purchased as coiled strips from the mill. The strip is fedcontinuously into a bank of rollers :which deform the strip by bendingit at the shoulders 14 forming the beaded margins 13 and the anchors1515.

Usually, in order to resist rusting, strips 11 and 12 are formed ofstainless steel, and in usual circumstances are approximately .0020 ofan inch thick. Those portions of the strip which are to contact with therubber seal 17 are coated with any of several proprietary rubber-metalbonding cements known to the art, such as, among others, natural rubber,chlorinated rubber, and vinyl nitrile compositions.

The die of an extrusion machine is arranged to allow the two strips,separated the required distance, to pass through the die while rubber inthe form, e.g., as shown at 17 issues through the die and enfolds thatportion of the strip which extends from the margins 13 to the shoulder14.

The configuration of the sealing element 17 is that of a two-barchevron, the top surface 18 of the upper bar 19 forming the wearingsurface of the seal, while the lower bar 21 extends from approximatelythe shoulder 14 to: the mid-point of the chevron, and forms an angle ofapproximately 30 to the horizontal.

Vulcanization can take place with properly compounded rubber compoundsin the die itself, but much more commonly the strips, after they havereceived the rubber sealing element, pass directly from the extrusionhead into an oven where the cure of the rubber compound is completed.The process is continuous.

Subsequently, the strips are cut to proper length, and then the metallicside walls are pushed toward each other, collapsing the rubber sealingmember 19 until it takes up the form shown in FIG. 4. Tie wires are thentied around the strip, and the strips shipped out in collapsedcondition.

Although ordinary steel may be used for the strip elements 11 and 12,contractors who will use this form of the invention will probablyspecify stainless steel. The resistance to corrosion which stainlesssteel insures, increases the life of the joint to such an extent thatthe higher cost of the stainless material is, in most instances,justified.

Seal 17 may have variable dimensions as the specifications demand, butfor the usual highway joint between concrete slabs, seal 17 is a tubularrubber extrusion, approximately one inch wide by inch deep. Its generalconfiguration is chevron-shaped, the upper margin dipping from theshoulders to the center at an angle of about 15, while the lower Walllies at an angle of approximately 30 to the horizontal.

A diaphragm 27 set on the median line extends between top wall 19 andthe bottom wall 21. The top wall 19 of the seal 17 is made materiallythicker (approximately .060") than the bottom wall 21 (approximately.020").

In this specification and the claims, the term rubber has been used inits present-day generic sense to indicate a distortable, resilientpolymeric material, and is not intended to indicate the chemical natureof the substance. Materials which have substantial oil resistance, andresist abrasion, and have the named rubber characteristics have provedsuitable as the distortable element in this invention e.g., the actualmaterial may be an artificial rubber such as chlorobutadiene, butadiene/styrene, butadiene/acrylonitrile types of rubbers, isobutene withisoprene or butadiene, ethylene-propylene mixtures, polyturethanes andpolyethylene vinyl acetate mixtures and copolymers. For highway service,rubbers made from the copolymer of butadiene and acrylonitrile will befound to fit most of the requirements and performance specifications.

In an alternative form of the invention, the process as described aboveis generally followed with the exception that the strips 11 and 12 areentirely coated with metal adhesive, and the entire strip passes throughthe rubber extrusion die or at right angles to the die. The extrudedrubber 22 covers both sides of both strips 11 and 12 including theanchor portions 1515 (see FIG. 2).

Because the entire surface of each metalic strip is covered with ajacket of rubber which is held to the strip by an overall vulcanizedbond, moisture working up through the subgrade cannot reach the steel.Sealing strips made by this alterntaive procedure ma utilize ordinarycarbon steels with complete satisfaction.

If the anchoring tongues 16 are required in the alternative form of thisinvention, the piercing of the strips 11 and 12 is done after the stripshave been covered with rubber jackets. This operation leaves a raw edgeof steel 23 but since the tongues are completely buried in concrete, thesteel is thoroughly protected.

The novel product of the present invention is employed in the followingmanner. The preformed joint seals, still held in the collapsed positionby the tie wires as above described, are planted in the wet concretefrom its surface downwardly. The preformed seal strip is pusheddownwardly until the top surface is flush with or slightly below thesurface of the concrete. Insertion may be made by hand, but in highwaywork, particularly, the strips are pushed into the wet concrete by ajoint-planting machine. As soon as the strip is planted, a highwaysurface is finished by running a float across the pavement.Subsequently, the edges of the slabs are hand finished. At this time, orlater, the tie wires are cut. The seal can now expand as the concreteshrinks as it cures.

The proper position of the seal in relation to the wearing surface ofthe slab is shown in FIG. 5. The seal 10 is bedded in the concrete sothat the margin 24 of rubber lies in the same plane as does the topsurface 25-25 of the abutting slabs 26-26. Ordinarily, the plow 'bladepasses over the seal without disturbing it to any material degree, butshould the concrete surface wear slightly, or should the finish of theconcrete at the margins 24 be slightly uneven, an advancing plow blademerely distorts the rubber and leaves the reinforcing strips 11 and 12undisturbed.

I claim:

1. A joint seal for concrete structures comprising two opposed metallicstrips having upper and lower margins and a web extending therebetween;a resilient, distortable sealing member positioned between said uppermargins formed of rubber and having side, upper and lower Walls, saidupper and lower walls being chevron-shaped and connected by a centrallylocated vertical diaphragm extending between said top and bottom walls,the said side walls of said member surrounding and embedding the saidupper margins of said metallic strips to prevent exposure of metal atthe wearing surface of the seal; and means for maintaining said stripsand said member in compressed relationship comprising tie wiresextending around the periphery of the joint seal whereby expansion ofsaid side strips and said member subsequent to the insertion of thejoint seal in the wet concrete is effected by severing said tire wires.

2. A seal as claimed in claim 1 having portions of its said web and saidlower margins bent outwardly to form anchoring members in the concrete.

3. A seal as claimed in claim 1 wherein the said side walls extenddownwardly below said body portion and enfold the entire extent of saidmetallic strips.

References Cited UNITED STATES PATENTS 2,156,681 5/1939 Dewhirst 94183,113,493 12/1963 Rinker 9418 3,276,335 10/ 1966 Middlestadt 94183,323,426 6/1967 Hahn 94-18 3,349,675 10/1967 Webb 9418 X NILE C. BYERS,Primary Examiner.

